Collectors It increases the non-wettability of ore particles by water, e. g., pine oils, xanthates and fatty acids.
Electromagnetic Separation
This method of concentration is employed when either the ore or the lmpurities associated with it are magnetic in nature. e. g., chromite,
FeCr2O4, containing magnetic SiliCIOUS gangue and wolframite FeWO4, Containing cassiterite, 8nO4( non-magnetic impurities) can be separated by this method.
Electrostatic Separation
This method is used for the separation of lead sulphide( good conductor) which is charged immediately in an electrostatic field and is thrown away from the roller from zinc sulphide( poor conductor) which is not charged and hence, drops vertically from the roller.
Chemical Method-Leaching
Leaching is the process in which the ore is concentrated by chemical reaction with a suitable reagent which dissolves the ore but not the impurities, e. g., bauxite is leached with a hot concentrated solution of NaOH which dissolves aluminium while other oxides( Fe2O3, TiO2, SiO2), remain undissolved and noble metals( Ag and Au) are leached with a dilute aqueous solution of NaCN or KCN in the presence of air.
Extraction of Crude Metals from Concentrated Ore
The concentrated ore is usually converted to oxide before reduction, as oxides are easier to reduce. Thus, isolation of crude metal from concentrated ore involves two major steps: